View source for Chemistry:Alcohol

{{pp-semi-indef}}
{{short description|Type of organic compound}}
[[File:Alcohol.png|upright=0.8|thumb|right|[[Physics:Ball-and-stick model|Ball-and-stick model]] of an alcohol molecule (R{{sub|3}}COH). The red and white balls represent the hydroxyl group (-OH). The three "R's" stand for carbon substituents or hydrogen atoms.<ref>{{cite web|title=alcohols|url=http://goldbook.iupac.org/A00204.html|work=IUPAC Gold Book|access-date=16 December 2013}}</ref>]]
[[File:Alcohol general.svg|upright=0.8|thumb|right|The bond angle between a hydroxyl group (-OH) and a chain of carbon atoms (R)]]

In [[Chemistry:Chemistry|chemistry]], '''alcohol''' is an [[Chemistry:Organic compound|organic compound]] that carries at least one hydroxyl [[Chemistry:Functional group|functional group]] (−OH) bound to a [[Chemistry:Saturated and unsaturated compounds|saturated]] [[Chemistry:Carbon|carbon]] atom.<ref>{{GoldBookRef | title = Alcohols | file = A00204}}</ref> The term alcohol originally referred to the primary alcohol [[Chemistry:Ethanol|ethanol]] (ethyl alcohol), which is [[Chemistry:Alcohol (drug)|used as a drug]] and is the main alcohol present in [[Chemistry:Alcoholic drink|alcoholic drink]]s. An important class of alcohols, of which [[Chemistry:Methanol|methanol]] and [[Chemistry:Ethanol|ethanol]] are the simplest members, includes all compounds for which the general formula is C{{sub|n}}H{{sub|2n+1}}OH. Simple monoalcohols that are the subject of this article include primary (RCH{{sub|2}}OH), secondary (R{{sub|2}}CHOH) and tertiary (R{{sub|3}}COH) alcohols.

The suffix ''-ol'' appears in the [[Chemistry:IUPAC nomenclature of organic chemistry|IUPAC chemical name]] of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix ''hydroxy-'' is used in its IUPAC name. The suffix ''-ol'' in non-IUPAC names (such as [[Chemistry:Paracetamol|paracetamol]] or [[Chemistry:Cholesterol|cholesterol]]) also typically indicates that the substance is an alcohol. However, many substances that contain hydroxyl functional groups (particularly sugars, such as [[Chemistry:Glucose|glucose]] and [[Chemistry:Sucrose|sucrose]]) have names which include neither the suffix ''-ol'', nor the prefix ''hydroxy-''. 

==History==
The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such as [[Biography:Aristotle|Aristotle]] (384–322 BCE), [[Biography:Theophrastus|Theophrastus]] (c. 371–287 BCE), and Pliny the Elder (23/24–79 CE).<ref>{{cite book|last1=Berthelot|first1=Marcellin|last2=Houdas|first2=Octave V.|year=1893|title=La Chimie au Moyen Âge|volume=Vol. I–III|location=Paris|publisher=Imprimerie nationale}} vol. I, p. 137.</ref> However, this did not immediately lead to the isolation of alcohol, even despite the development of more advanced distillation techniques in second- and third-century Roman Egypt.<ref>{{harvnb|Berthelot|Houdas|1893|loc=vol. I, pp. 138-139}}.</ref> An important recognition, first found in one of the writings attributed to [[Biography:Jabir ibn Hayyan|Jābir ibn Ḥayyān]] (ninth century CE), was that by [[Chemistry:Salt-effect distillation|adding salt]] to boiling wine, which increases the wine's [[Chemistry:Relative volatility|relative volatility]], the flammability of the resulting vapors may be enhanced.<ref>{{cite book|last1=al-Hassan|first1=Ahmad Y.|year=2009|chapter=Alcohol and the Distillation of Wine in Arabic Sources from the 8th Century|title=Studies in al-Kimya': Critical Issues in Latin and Arabic Alchemy and Chemistry|location=Hildesheim|publisher=Georg Olms Verlag|pages=283–298}} (same content also available on [http://www.history-science-technology.com/notes/notes7.html the author's website]).</ref> The distillation of wine is attested in Arabic works attributed to [[Biography:Al-Kindi|al-Kindī]] (c. 801–873 CE) and to [[Biography:Al-Farabi|al-Fārābī]] (c. 872–950), and in the 28th book of al-Zahrāwī's (Latin: Abulcasis, 936–1013) ''Kitāb al-Taṣrīf'' (later translated into Latin as ''Liber servatoris'').<ref>{{harvnb|al-Hassan|2009}} (same content also available on [http://www.history-science-technology.com/notes/notes7.html the author's website]); cf. {{harvnb|Berthelot|Houdas|1893|loc=vol. I, pp. 141, 143}}. Sometimes, sulfur was also added to the wine (see {{harvnb|Berthelot|Houdas|1893|loc=vol. I, p. 143}}).</ref> In the twelfth century, recipes for the production of ''aqua ardens'' ("burning water", i.e., alcohol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists.<ref>{{cite book|last=Multhauf|first=Robert P.|author-link=Robert P. Multhauf|year=1966|title=The Origins of Chemistry|location=London|publisher=Oldbourne|isbn=9782881245947}} pp. 204-206.</ref> Its medicinal properties were studied by Arnald of Villanova (1240–1311 CE) and John of Rupescissa (c. 1310–1366), the latter of whom regarded it as a life-preserving substance able to prevent all diseases (the ''aqua vitae'' or "water of life", also called by John the ''[[Philosophy:Aether (classical element)|quintessence]]'' of wine).<ref>{{cite book|last=Principe|first=Lawrence M.|author-link=Lawrence M. Principe|year=2013|title=The Secrets of Alchemy|location=Chicago|publisher=The University of Chicago Press|isbn=978-0226103792}} pp. 69-71.</ref>

==Nomenclature==
===Etymology===
The word "alcohol" is from the Arabic ''kohl'' ({{lang-ar|الكحل|al-kuḥl}}), a powder used as an eyeliner.<ref>{{cite encyclopedia |url=https://www.etymonline.com/search?q=alcohol |title=Alcohol |access-date=17 May 2018 |dictionary=Etymonline |last=Harper |first=Douglas |publisher=MaoningTech}}</ref> Al- is the Arabic definite article, equivalent to ''the'' in English. ''Alcohol'' was originally used for the very fine powder produced by the sublimation of the natural mineral [[Chemistry:Stibnite|stibnite]] to form [[Chemistry:Antimony trisulfide|antimony trisulfide]] {{chem|Sb|2|S|3}}. It was considered to be the essence or "spirit" of this mineral. It was used as an [[Chemistry:Antiseptic|antiseptic]], eyeliner, and cosmetic. The meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when "spirits" was a synonym for hard liquor.<ref>{{cite encyclopedia |url=http://www.vias.org/encyclopedia/Alcohol_004.html |encyclopedia=VIAS Encyclopedia |title=Etymology of the Word "Alcohol" |first=H. |last=Lohninger |date=21 December 2004 |access-date=17 May 2018}}</ref>

Bartholomew Traheron, in his 1543 translation of John of Vigo, introduces the word as a term used by "barbarous" authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or (as I fynde it sometymes wryten) alcofoll, for moost fine poudre."<ref name="oed">{{cite encyclopedia |title=alcohol, n. |dictionary=OED Online |publisher=[[Organization:Oxford University Press|Oxford University Press]] |date=15 November 2016}}</ref>

The 1657 ''Lexicon Chymicum'', by William Johnson glosses the word as "antimonium sive stibium."<ref>{{cite book |url=https://books.google.com?id=d645AAAAcAAJ&printsec=frontcover |title=Lexicon Chymicum |last=Johnson |first=William |year=1652}}</ref> By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine," the distilled essence of wine. Libavius in ''Alchymia'' (1594) refers to "vini alcohol vel vinum alcalisatum". Johnson (1657) glosses ''alcohol vini'' as "quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat." The word's meaning became restricted to "spirit of wine" (the chemical known today as [[Chemistry:Ethanol|ethanol]]) in the 18th century and was extended to the class of substances so-called as "alcohols" in modern chemistry after 1850.<ref name="oed"/>

The term ''ethanol'' was invented in 1892, blending "[[Chemistry:Ethane|ethane]]" with the "-ol" ending of "alcohol", which was generalized as a libfix.<ref>{{cite journal |journal=Proc. Chem. Soc. |date=8 July 1892 |page=128 |title=Contributions to an international system of nomenclature. The nomenclature of cycloids |first=Henry E. |last=Armstrong |quote=As ol is indicative of an OH derivative, there seems no reason why the simple word acid should not connote carboxyl, and why al should not connote COH; the names ethanol ethanal and ethanoic acid or simply ethane acid would then stand for the OH, COH and COOH derivatives of ethane. |doi=10.1039/PL8920800127 |volume=8 |issue=114 |url=https://books.google.com/books?id=ax1LAAAAYAAJ&pg=PA128}}</ref>

===Systematic names===
[[Chemistry:Chemical nomenclature|IUPAC nomenclature]] is used in scientific publications and where precise identification of the substance is important, especially in cases where the relative complexity of the molecule does not make such a systematic name unwieldy. In naming simple alcohols, the name of the alkane chain loses the terminal ''e'' and adds the suffix ''-ol'', ''e.g.'', as in "ethanol" from the alkane chain name "ethane".<ref name=reusch-alcohols>{{cite web | author = William Reusch | work = VirtualText of Organic Chemistry | title = Alcohols | url = http://www.cem.msu.edu/~reusch/VirtualText/alcohol1.htm#alcnom | access-date = 14 September 2007 | archive-url = https://web.archive.org/web/20070919162404/http://www.cem.msu.edu/~reusch/VirtualText/alcohol1.htm#alcnom | archive-date = 19 September 2007 | url-status = dead}}</ref> When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the ''-ol'': [[Chemistry:Propan-1-ol|propan-1-ol]] for {{chem|CH|3|CH|2|CH|2|OH}}, [[Chemistry:Isopropyl alcohol|propan-2-ol]] for {{chem|CH|3|CH(OH)|CH|3}}. If a higher priority group is present (such as an [[Chemistry:Aldehyde|aldehyde]], [[Chemistry:Ketone|ketone]], or [[Chemistry:Carboxylic acid|carboxylic acid]]), then the prefix ''hydroxy-''is used,<ref name = reusch-alcohols/> e.g., as in 1-hydroxy-2-propanone ({{chem|CH|3|C(O)|CH|2|OH}}).<ref>Organic chemistry IUPAC nomenclature. [http://www.acdlabs.com/iupac/nomenclature/79/r79_202.htm Alcohols Rule C-201].</ref>
{| class="wikitable"
|+ Some examples of simple alcohols and how to name them
|- style="text-align: center"
| CH{{sub|3}}–CH{{sub|2}}–CH{{sub|2}}–OH
| [[File:Propan-2-ol displayed.svg|85px]]
| [[File:Cyclohexanol displayed.svg|110px]]
| [[File:2-methylpropan-1-ol displayed.svg|100px]]
| [[File:2-methylbutan-2-ol displayed.svg|100px]]
|- style="text-align: center"
| [[File:Propan-1-ol.svg|100px]]
| [[File:2-Propanol.svg|60px]]
| [[File:Cyclohexanol acsv.svg|100px]]
| [[File:Isobutanol.svg|110px]]
| [[File:2-Methyl-2-butanol FormulaV1-Seite001.svg|100px]]
|-
| ''n''-propyl alcohol,<br />propan-1-ol, or<br />1-propanol
| isopropyl alcohol,<br />propan-2-ol, or<br />2-propanol
| cyclohexanol
| isobutyl alcohol,<br />2-methylpropan-1-ol, or<br />2-methyl-1-propanol
| ''tert''-amyl alcohol,<br />2-methylbutan-2-ol, or<br />2-methyl-2-butanol
|-
| A primary alcohol
| A secondary alcohol
| A secondary alcohol
| A primary alcohol
| A tertiary alcohol
|}
In cases where the OH functional group is bonded to an sp<sup>2</sup> carbon on an [[Chemistry:Aromatic compound|aromatic ring]] the molecule is known as a [[Chemistry:Phenols|phenol]], and is named using the IUPAC rules for naming phenols.<ref>[http://www.acdlabs.com/iupac/nomenclature/79/r79_212.htm Organic Chemistry Nomenclature Rule C-203: Phenols]</ref>

===Common names===
In other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word "alcohol", e.g., [[Chemistry:Methyl group|methyl]] alcohol, [[Chemistry:Ethyl group|ethyl]] alcohol. Propyl alcohol may be [[Chemistry:Propanol|''n''-propyl alcohol]] or [[Chemistry:Isopropyl alcohol|isopropyl alcohol]], depending on whether the hydroxyl group is bonded to the end or middle carbon on the straight [[Chemistry:Propane|propane]] chain. As described under systematic naming, if another group on the molecule takes priority, the alcohol moiety is often indicated using the "hydroxy-" prefix.<ref name="NamingRules">{{cite web|title=How to name organic compounds using the IUPAC rules|url=http://www.chem.uiuc.edu/GenChemReferences/nomenclature_rules.html|website=www.chem.uiuc.edu|publisher=THE DEPARTMENT OF CHEMISTRY AT THE UNIVERSITY OF ILLINOIS|access-date=14 November 2016}}</ref>

{{anchor|secondary|tertiary}}
Alcohols are then classified into primary, secondary (''sec-'', ''s-''), and tertiary (''tert-'', ''t-''), based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl [[Chemistry:Functional group|functional group]]. (The respective numeric shorthands 1°, 2°, and 3° are also sometimes used in informal settings.<ref>{{cite web|last1=Reusch|first1=William|title=Nomenclature of Alcohols|url=http://chemwiki.ucdavis.edu/Organic_Chemistry/Alcohols/Nomenclature_of_Alcohols|website=chemwiki.ucdavis.edu/|date=2 October 2013|access-date=17 March 2015}}</ref>) The primary alcohols have general formulas RCH{{sub|2}}OH. The simplest primary alcohol is methanol (CH{{sub|3}}OH), for which R=H, and the next is ethanol, for which R=CH{{sub|3}}, the [[Chemistry:Methyl group|methyl group]]. Secondary alcohols are those of the form RR'CHOH, the simplest of which is 2-propanol (R=R'=CH{{sub|3}}). For the tertiary alcohols the general form is RR'R"COH. The simplest example is tert-butanol (2-methylpropan-2-ol), for which each of R, R', and R" is CH{{sub|3}}. In these shorthands, R, R', and R" represent substituents, alkyl or other attached, generally organic groups.

In archaic nomenclature, alcohols can be named as derivatives of methanol using "-carbinol" as the ending. For instance, (CH{{sub|3}}){{sub|3}}COH can be named trimethylcarbinol.

{| class="wikitable" style="width:600px; white-space:nowrap;" 
! Type
! Formula
! IUPAC Name
! Common name
|-
| rowspan="6"|''Monohydric<br />alcohols''
| CH{{sub|3}}OH
| [[Chemistry:Methanol|Methanol]]
| Wood alcohol
|-
| C{{sub|2}}H{{sub|5}}OH
| [[Chemistry:Ethanol|Ethanol]]
| Alcohol
|-
| C{{sub|3}}H{{sub|7}}OH
| Propan-2-ol
| Isopropyl alcohol,<br />Rubbing alcohol
|-
| C{{sub|4}}H{{sub|9}}OH
| Butan-1-ol 
| Butanol,<br />Butyl alcohol
|-
| C{{sub|5}}H{{sub|11}}OH
| Pentan-1-ol
| Pentanol,<br />Amyl alcohol
|-
| C{{sub|16}}H{{sub|33}}OH
| Hexadecan-1-ol
| [[Chemistry:Cetyl alcohol|Cetyl alcohol]]
|-
| rowspan="7"|''Polyhydric<br />alcohols''
| C{{sub|2}}H{{sub|4}}(OH){{sub|2}}
| Ethane-1,2-diol
| [[Chemistry:Ethylene glycol|Ethylene glycol]]
|-
| C{{sub|3}}H{{sub|6}}(OH){{sub|2}}
| Propane-1,2-diol
| [[Chemistry:Propylene glycol|Propylene glycol]]
|-
| C{{sub|3}}H{{sub|5}}(OH){{sub|3}}
| Propane-1,2,3-triol
| [[Chemistry:Glycerol|Glycerol]]
|-
| C{{sub|4}}H{{sub|6}}(OH){{sub|4}}
| Butane-1,2,3,4-tetraol
| [[Chemistry:Erythritol|Erythritol]],<br />[[Chemistry:Threitol|Threitol]]
|-
| C{{sub|5}}H{{sub|7}}(OH){{sub|5}}
| Pentane-1,2,3,4,5-pentol
| [[Chemistry:Xylitol|Xylitol]]
|-
| C{{sub|6}}H{{sub|8}}(OH){{sub|6}}
| hexane-1,2,3,4,5,6-hexol
| [[Chemistry:Mannitol|Mannitol]],<br />[[Chemistry:Sorbitol|Sorbitol]]
|-
| C{{sub|7}}H{{sub|9}}(OH){{sub|7}}
| Heptane-1,2,3,4,5,6,7-heptol
| [[Chemistry:Volemitol|Volemitol]]
|-
| rowspan="3"|''Unsaturated<br />aliphatic<br />alcohols''
| C{{sub|3}}H{{sub|5}}OH
| Prop-2-ene-1-ol
| [[Chemistry:Allyl alcohol|Allyl alcohol]]
|-
| C{{sub|10}}H{{sub|17}}OH
| 3,7-Dimethylocta-2,6-dien-1-ol
| [[Chemistry:Geraniol|Geraniol]]
|-
|C{{sub|3}}H{{sub|3}}OH
| Prop-2-yn-1-ol
| [[Chemistry:Propargyl alcohol|Propargyl alcohol]]
|-
| rowspan="2"|''Alicyclic<br />alcohols''
| C{{sub|6}}H{{sub|6}}(OH){{sub|6}}
| Cyclohexane-1,2,3,4,5,6-hexol
| [[Chemistry:Inositol|Inositol]]
|-
| C{{sub|10}}H{{sub|19}}OH
| 5-Methyl-2-(propan-2-yl)cyclohexan-1-ol
| [[Chemistry:Menthol|Menthol]]
|}

==Applications==
[[File:Alcohol by Country.png|thumb|upright=0.9|Total recorded alcohol per capita consumption (15+), in litres of pure ethanol<ref>{{cite web|url=https://www.who.int/entity/substance_abuse/publications/global_status_report_2004_overview.pdf |title=Global Status Report on Alcohol 2004 |access-date=28 November 2010}}</ref>]]

Alcohols have a long history of myriad uses. For simple mono-alcohols, which is the focus on this article, the following are most important industrial alcohols:<ref name="Ullmann1">{{Ullmann | first1 = Jürgen | last1 = Falbe | first2 = Helmut | last2 = Bahrmann | first3 = Wolfgang | last3 = Lipps | first4 = Dieter | last4 = Mayer | title = Alcohols, Aliphatic | doi = 10.1002/14356007.a01_279}}.</ref>
*methanol, mainly for the production of [[Physics:Formaldehyde|formaldehyde]] and as a fuel additive
*ethanol, mainly for alcoholic beverages, fuel additive, solvent
*1-propanol, 1-butanol, and isobutyl alcohol for use as a solvent and precursor to solvents
*C6–C11 alcohols used for [[Chemistry:Plasticizer|plasticizer]]s, e.g. in polyvinylchloride
*fatty alcohol (C12–C18), precursors to detergents
Methanol is the most common industrial alcohol, with about 12 million tons/y produced in 1980. The combined capacity of the other alcohols is about the same, distributed roughly equally.<ref name="Ullmann1"/>

==Toxicity==
{{main|Chemistry:Ethanol|Chemistry:Methanol}}
With respect to acute toxicity, simple alcohols have low acute toxicities. Doses of several milliliters are tolerated. For pentanols, [[Chemistry:Hexanol|hexanol]]s, [[Chemistry:Octanol|octanol]]s and longer alcohols, LD50 range from 2–5 g/kg (rats, oral). Methanol and ethanol are less acutely toxic. All alcohols are mild skin irritants.<ref name="Ullmann1"/>

The metabolism of methanol (and ethylene glycol) is affected by the presence of ethanol, which has a higher affinity for liver alcohol dehydrogenase. In this way methanol will be excreted intact in urine.<ref name="Schep">{{cite journal |vauthors=Schep LJ, Slaughter RJ, Vale JA, Beasley DM |title=A seaman with blindness and confusion |journal=BMJ|volume=339 |pages=b3929 |date=30 September 2009|url=http://www.bmj.com/cgi/content/full/339/sep30_1/b3929|doi=10.1136/bmj.b3929|pmid=19793790|s2cid=6367081 }}</ref><ref>{{cite journal | last1 = Zimmerman | first1 = HE | last2 = Burkhart | first2 = KK | last3 = Donovan | first3 = JW | title = Ethylene glycol and methanol poisoning: diagnosis and treatment | journal = Journal of Emergency Nursing | volume = 25 | issue = 2 | pages = 116–20 | year = 1999 | pmid = 10097201 | name-list-style=vanc | doi = 10.1016/S0099-1767(99)70156-X }}</ref><ref>{{cite journal | last1 = Lobert | first1 = S | title = Ethanol, isopropanol, methanol, and ethylene glycol poisoning | journal = Critical Care Nurse | volume = 20 | issue = 6 | pages = 41–7 | year = 2000 | pmid = 11878258 | name-list-style=vanc| doi = 10.4037/ccn2000.20.6.41 }}</ref>

==Physical properties==
In general, the [[Chemistry:Hydroxyl group|hydroxyl group]] makes alcohols polar. Those groups can form [[Chemistry:Hydrogen bond|hydrogen bond]]s to one another and to most other compounds. Owing to the presence of the polar OH alcohols are more water-soluble than simple hydrocarbons. Methanol, ethanol, and propanol are [[Chemistry:Miscible|miscible]] in water. [[Chemistry:N-Butanol|Butanol]], with a four-carbon chain, is moderately soluble.

Because of hydrogen bonding, alcohols tend to have higher boiling points than comparable [[Chemistry:Hydrocarbon|hydrocarbon]]s and [[Chemistry:Ether|ether]]s. The boiling point of the alcohol ethanol is 78.29&nbsp;°C, compared to 69&nbsp;°C for the hydrocarbon [[Chemistry:Hexane|hexane]], and 34.6&nbsp;°C for [[Chemistry:Diethyl ether|diethyl ether]].

==Occurrence in nature==
Simple alcohols are found widely in nature. Ethanol is the most prominent because it is the product of fermentation, a major energy-producing pathway. The other simple alcohols are formed in only trace amounts. More complex alcohols however are pervasive, as manifested in sugars, some amino acids, and fatty acids.

==Production==

===Ziegler and oxo processes===
In the [[Chemistry:Ziegler process|Ziegler process]], linear alcohols are produced from ethylene and [[Chemistry:Triethylaluminium|triethylaluminium]] followed by oxidation and hydrolysis.<ref name="Ullmann1"/> An idealized synthesis of 1-octanol is shown:

:Al(C{{sub|2}}H{{sub|5}}){{sub|3}}  +  9 C{{sub|2}}H{{sub|4}}   →  Al(C{{sub|8}}H{{sub|17}}){{sub|3}}
:Al(C{{sub|8}}H{{sub|17}}){{sub|3}} +  3 O  +  3 H{{sub|2}}O  →  3 HOC{{sub|8}}H{{sub|17}}  +  Al(OH){{sub|3}}

The process generates a range of alcohols that are separated by [[Distillation|distillation]].

Many higher alcohols are produced by [[Chemistry:Hydroformylation|hydroformylation]] of alkenes followed by hydrogenation. When applied to a terminal alkene, as is common, one typically obtains a linear alcohol:<ref name="Ullmann1"/>

:RCH=CH{{sub|2}}  +  H{{sub|2}}  +  CO   →  RCH{{sub|2}}CH{{sub|2}}CHO
:RCH{{sub|2}}CH{{sub|2}}CHO +  3 H{{sub|2}}  →  RCH{{sub|2}}CH{{sub|2}}CH{{sub|2}}OH

Such processes give [[Chemistry:Fatty alcohol|fatty alcohol]]s, which are useful for detergents.

===Hydration reactions===
Some low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes. Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method. Two implementations are employed, the direct and indirect methods. The direct method avoids the formation of stable intermediates, typically using acid catalysts. In the indirect method, the alkene is converted to the sulfate ester, which is subsequently hydrolyzed. The direct [[Chemistry:Hydration reaction|hydration]] using [[Chemistry:Ethylene|ethylene]] ([[Chemistry:Ethanol#Ethylene hydration|ethylene hydration]])<ref name="ECT4 820">{{cite book |author =Lodgsdon J.E. |year=1994 |chapter=Ethanol |editor=Kroschwitz J.I. |title=Encyclopedia of Chemical Technology| edition=4th |volume=9 |page=820 |location=New York |publisher=John Wiley & Sons |isbn=978-0-471-52677-3}}</ref> or other alkenes from [[Chemistry:Cracking|cracking]] of fractions of distilled crude oil.

Hydration is also used industrially to produce the diol [[Chemistry:Ethylene glycol|ethylene glycol]] from [[Chemistry:Ethylene oxide|ethylene oxide]].

===Biological routes===
Ethanol is obtained by fermentation using [[Chemistry:Glucose|glucose]] produced from sugar from the [[Chemistry:Hydrolysis|hydrolysis]] of [[Chemistry:Starch|starch]], in the presence of yeast and temperature of less than 37&nbsp;°C to produce ethanol. For instance, such a process might proceed by the conversion of [[Chemistry:Sucrose|sucrose]] by the enzyme [[Biology:Invertase|invertase]] into glucose and [[Chemistry:Fructose|fructose]], then the conversion of glucose by the enzyme complex [[Biology:Zymase|zymase]] into ethanol and carbon dioxide.

Several species of the benign bacteria in the intestine use fermentation as a form of anaerobic metabolism. This [[Biology:Metabolism|metabolic]] reaction produces ethanol as a waste product. Thus, human bodies contain some quantity of alcohol endogenously produced by these bacteria. In rare cases, this can be sufficient to cause "[[Medicine:Auto-brewery syndrome|auto-brewery syndrome]]" in which intoxicating quantities of alcohol are produced.<ref>{{cite journal |doi=10.1007/BF01873798 |pmid=6760604 |title=Endogenous alcohol production by intestinal fermentation in sudden infant death |author1=P. Geertinger MD |author2=J. Bodenhoff |author3=K. Helweg-Larsen |author4=A. Lund |s2cid=29917601 |date=1 September 1982 |journal=Zeitschrift für Rechtsmedizin |publisher=Springer-Verlag |volume=89 |issue=3 |pages=167–172}}</ref><ref>{{cite journal |pmid=10976182 |title=Endogenous ethanol 'auto-brewery syndrome' as a drunk-driving defence challenge |vauthors=Logan BK, Jones AW |s2cid=6926029 |date=July 2000 |journal=Medicine, Science, and the Law |volume=40 |issue=3 |pages=206–15 |doi=10.1177/002580240004000304 }}</ref><ref>{{cite web |url=http://www.straightdope.com/columns/read/2677/designated-drunk |title=Designated drunk: Can you get intoxicated without actually drinking alcohol? |author =Cecil Adams |date=20 October 2006 |work=The Straight Dope |access-date=27 February 2013}}</ref>

Like ethanol, [[Chemistry:N-Butanol|butanol]] can be produced by fermentation processes. Saccharomyces yeast are known to produce these higher alcohols at temperatures above {{convert|75|°F|°C|abbr=on}}. The bacterium ''[[Biology:Clostridium acetobutylicum|Clostridium acetobutylicum]]'' can feed on [[Chemistry:Cellulose|cellulose]] to produce butanol on an industrial scale.<ref name="Zverlov et al">{{cite journal|last1=Zverlov|first1=W|last2=Berezina|first2=O|last3=Velikodvorskaya|first3=GA|last4=Schwarz|first4=WH|s2cid=24074264|title=Bacterial acetone and butanol production by industrial fermentation in the Soviet Union: use of hydrolyzed agricultural waste for biorefinery.|journal=Applied Microbiology and Biotechnology|date=August 2006|volume=71|issue=5|pages=587–97|doi=10.1007/s00253-006-0445-z|pmid=16685494}}</ref>

====Substitution====
Primary alkyl halides react with aqueous [[Chemistry:Sodium hydroxide|NaOH]] or [[Chemistry:Potassium hydroxide|KOH]] mainly to primary alcohols in nucleophilic aliphatic substitution. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead). [[Chemistry:Grignard reagent|Grignard reagent]]s react with carbonyl groups to secondary and tertiary alcohols. Related reactions are the [[Chemistry:Barbier reaction|Barbier reaction]] and the Nozaki-Hiyama reaction.

====Reduction====
Aldehydes or [[Chemistry:Ketone|ketone]]s are [[Chemistry:Redox|reduced]] with [[Chemistry:Sodium borohydride|sodium borohydride]] or [[Chemistry:Lithium aluminium hydride|lithium aluminium hydride]] (after an acidic workup). Another reduction by aluminiumisopropylates is the Meerwein-Ponndorf-Verley reduction. [[Physics:Noyori asymmetric hydrogenation|Noyori asymmetric hydrogenation]] is the asymmetric reduction of β-keto-esters.

====Hydrolysis====
Alkenes engage in an acid catalysed [[Chemistry:Hydration reaction|hydration reaction]] using concentrated sulfuric acid as a catalyst that gives usually secondary or tertiary alcohols. The hydroboration-oxidation and oxymercuration-reduction of alkenes are more reliable in organic synthesis. Alkenes react with NBS and water in halohydrin formation reaction. [[Chemistry:Amine|Amine]]s can be converted to diazonium salts, which are then hydrolyzed.

The formation of a secondary alcohol via reduction and hydration is shown:

:[[File:Secondary alcohol formation-diagram.svg|frameless|upright=1.6|Preparation of a secondary alcohol]]

==Reactions==<!-- This section is linked from [[Chemistry:Organic reaction|Organic reaction]] -->

===Deprotonation===
With a pK{{sub|a}} of around 16–19, they are, in general, slightly weaker [[Chemistry:Acid|acid]]s than [[Chemistry:Water (molecule)|water]]. With strong bases such as [[Chemistry:Sodium hydride|sodium hydride]] or [[Chemistry:Sodium|sodium]] they form [[Chemistry:Salt|salt]]s called '''[[Chemistry:Alkoxide|alkoxide]]s''', with the general formula [[Chemistry:Alkyl|R]]O<sup>−</sup> [[Chemistry:Metal|M]]<sup>+</sup>.
: 2 R-OH + 2 NaH  → 2 R-O<sup>−</sup>Na<sup>+</sup> + 2 H{{sub|2}}
: 2 R-OH + 2 Na   →   2 R-O<sup>−</sup>Na<sup>+</sup> + H{{sub|2}}

The acidity of alcohols is strongly affected by [[Chemistry:Solvation|solvation]]. In the gas phase, alcohols are more acidic than in water.<ref>{{March6th}}</ref>

===Nucleophilic substitution===
The OH group is not a good [[Chemistry:Leaving group|leaving group]] in [[Chemistry:Nucleophilic substitution|nucleophilic substitution]] reactions, so neutral alcohols do not react in such reactions. However, if the oxygen is first protonated to give R−OH{{sub|2}}<sup>+</sup>, the leaving group ([[Chemistry:Water (molecule)|water]]) is much more stable, and the nucleophilic substitution can take place. For instance, tertiary alcohols react with [[Chemistry:Hydrochloric acid|hydrochloric acid]] to produce tertiary alkyl halides, where the [[Chemistry:Hydroxyl group|hydroxyl group]] is replaced by a [[Chemistry:Chlorine|chlorine]] atom by unimolecular nucleophilic substitution. If primary or secondary alcohols are to be reacted with [[Chemistry:Hydrochloric acid|hydrochloric acid]], an activator such as [[Chemistry:Zinc chloride|zinc chloride]] is needed. In alternative fashion, the conversion may be performed directly using [[Chemistry:Thionyl chloride|thionyl chloride]].<sup>[1]</sup>

[[File:Alcohol reaction examples.svg|frameless|upright=3.2|Some simple conversions of alcohols to alkyl chlorides]]

Alcohols may, likewise, be converted to alkyl bromides using [[Chemistry:Hydrobromic acid|hydrobromic acid]] or [[Chemistry:Phosphorus tribromide|phosphorus tribromide]], for example:

: 3 R-OH + PBr{{sub|3}} → 3 RBr + H{{sub|3}}PO{{sub|3}}

In the Barton-McCombie deoxygenation an alcohol is deoxygenated to an [[Chemistry:Alkane|alkane]] with tributyltin hydride or a trimethylborane-water complex in a [[Chemistry:Radical substitution|radical substitution]] reaction.

===Dehydration===
Meanwhile, the oxygen atom has [[Chemistry:Lone pair|lone pair]]s of nonbonded electrons that render it weakly [[Chemistry:Base|basic]] in the presence of strong acids such as [[Chemistry:Sulfuric acid|sulfuric acid]]. For example, with methanol:

[[File:Methanol acid base.svg|frameless|upright=2.25|Acidity & basicity of methanol]]

Upon treatment with strong acids, alcohols undergo the E1 [[Chemistry:Elimination reaction|elimination reaction]] to produce [[Chemistry:Alkene|alkene]]s. The reaction, in general, obeys Zaitsev's Rule, which states that the most stable (usually the most substituted) alkene is formed. Tertiary alcohols eliminate easily at just above room temperature, but primary alcohols require a higher temperature.

This is a diagram of acid catalysed dehydration of ethanol to produce [[Chemistry:Ethylene|ethylene]]:

[[File:DehydrationOfAlcoholWithH-.png|frameless|upright=2.5]]

A more controlled elimination reaction requires the formation of the xanthate ester.

===Protonolysis===
Tertiary alcohols react with strong acids to generate carbocations. The reaction is related to their dehydration, e.g. isobutylene from tert-butyl alcohol. A special kind of dehydration reaction involves [[Chemistry:Triphenylmethanol|triphenylmethanol]] and especially its amine-substituted derivatives. When treated with acid, these alcohols lose water to give stable carbocations, which are commercial dyes.<ref name=Ull>{{Ullmann's | last1 = Gessner | first1 = Thomas | last2 = Mayer | first2 = Udo | title = Triarylmethane and Diarylmethane Dyes | year = 2000 | doi = 10.1002/14356007.a27_179}}</ref>
thumb|right|322px|Preparation of [[crystal violet by protonolysis of the tertiary alcohol.]]

===Esterification===
Alcohol and [[Chemistry:Carboxylic acid|carboxylic acid]]s react in the so-called Fischer esterification. The reaction usually requires a [[Chemistry:Catalyst|catalyst]], such as concentrated sulfuric acid:
: R-OH + R'-CO{{sub|2}}H → R'-CO{{sub|2}}R + H{{sub|2}}O
Other types of ester are prepared in a similar manner{{snd}} for example, [[Chemistry:Tosyl|tosyl]] (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.

===Oxidation===
{{Main|Chemistry:Alcohol oxidation}}
Primary alcohols (R-CH{{sub|2}}OH) can be oxidized either to [[Chemistry:Aldehyde|aldehyde]]s (R-CHO) or to [[Chemistry:Carboxylic acid|carboxylic acid]]s (R-CO{{sub|2}}H). The oxidation of secondary alcohols (R<sup>1</sup>R<sup>2</sup>CH-OH) normally terminates at the [[Chemistry:Ketone|ketone]] (R<sup>1</sup>R<sup>2</sup>C=O) stage. Tertiary alcohols (R<sup>1</sup>R<sup>2</sup>R<sup>3</sup>C-OH) are resistant to oxidation.

The direct [[Chemistry:Oxidation of primary alcohols to carboxylic acids|oxidation of primary alcohols to carboxylic acids]] normally proceeds via the corresponding aldehyde, which is transformed via an ''aldehyde hydrate'' (R-CH(OH){{sub|2}}) by reaction with water before it can be further oxidized to the carboxylic acid.

[[File:Alcohol to aldehyde to acid.png|upright=2.25|thumb|center|Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates]]

Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the [[Chemistry:Oxidation of secondary alcohols to ketones|oxidation of secondary alcohols to ketones]]. These include [[Chemistry:Collins reagent|Collins reagent]] and Dess-Martin periodinane. The direct oxidation of primary alcohols to carboxylic acids can be carried out using [[Chemistry:Potassium permanganate|potassium permanganate]] or the [[Chemistry:Jones reagent|Jones reagent]].

==See also==
{{div col|colwidth=20em}}
* [[Biology:Enol|Enol]]
* Ethanol fuel
* [[Chemistry:Fatty alcohol|Fatty alcohol]]
* Index of alcohol-related articles
* [[Chemistry:List of alcohols|List of alcohols]]
* [[Chemistry:Lucas' reagent|Lucas test]]
* [[Chemistry:Polyol|Polyol]]
* [[Chemistry:Rubbing alcohol|Rubbing alcohol]]
* [[Chemistry:Sugar alcohol|Sugar alcohol]]
* [[Chemistry:Transesterification|Transesterification]]
{{div col end}}

==Notes==
{{Reflist|30em}}

==References==
* {{cite book |title=The World in So Many Words |first=Allan A. |last=Metcalf |publisher=Houghton Mifflin |year=1999 |isbn=0-395-95920-9 <!--|url=https://books.google.com/books?id=4O0W5XyQVCYC&pg=PA123&dq=sash+etymology+arabic&lr=&as_brr=3&sig=iuzjUzyPphZKCIJLAwJZE7beIEI#PPA123,M1-->}}

==External links==

{{Alcohols|state=collapsed}}
{{Functional group}}
{{Poisoning and toxicity}}

[[Category:Alcohols| ]]
[[Category:Antiseptics]]
[[Category:Functional groups]]

{{Sourceattribution|Alcohol|1}}